[Background]Traveling-wave tubes(TWTs)are widely applied in radar,imaging,and military systems owing to their excellent amplification characteristics.Miniaturization and integration are critical to the future of TWTs,...[Background]Traveling-wave tubes(TWTs)are widely applied in radar,imaging,and military systems owing to their excellent amplification characteristics.Miniaturization and integration are critical to the future of TWTs,with multi-channel slow-wave structures(SWSs)forming the foundation for their realization in high-power vacuum electronic devices.[Purpose]To provide design insights for multi-channel TWTs and simultaneously enhance their output power,a W-band folded-waveguide TWT with dual electron beams and H-plane power combining was proposed.[Methods]Three-dimensional electromagnetic simulations in CST were conducted to verify the highfrequency characteristics,electric field distribution,and amplification performance of the proposed SWS,thereby confirming the validity of the design.[Results]Results indicate that the designed TWT achieves a transmission bandwidth of 10 GHz.With an electron beam voltage of 17.9 kV and a current of 0.35 A,the output power reaches 450 W at 94 GHz,corresponding to an efficiency of 7.18%and a gain of 23.5 dB.Moreover,under fixed beam voltage and current,the TWT delivers over 200 W output power across 91–99 GHz,with a 3 dB bandwidth of 91–98.5 GHz.The particle voltage distribution after modulation further validates the mode analysis.[Conclusions]These results demonstrate the feasibility of compact dual-beam power-combining structures and provide useful guidance for the design of future multi-channel TWTs.展开更多
A power amplifier MIC with power combining based on AlGaN/GaN HEMTs was fabricated and measured. The amplifier consists of four 10 × 120μm transistors. A Wilkinson splitters and combining were used to divide and...A power amplifier MIC with power combining based on AlGaN/GaN HEMTs was fabricated and measured. The amplifier consists of four 10 × 120μm transistors. A Wilkinson splitters and combining were used to divide and combine the power. By biasing the amplifier at VDS = 40V, IDS = 0.9A, a maximum CW output power of 41.4dBm with a maximum power added efficiency （PAE） of 32.54% and a power combine efficiency of 69% was achieved at 5.4GHz.展开更多
A MIC power amplifier with power combining based on InGaP/GaAs HBT is developed and measured for the application of the latest high power amplifier stage of the X-band. A novel InGaP/GaAs HBT power transistor with an ...A MIC power amplifier with power combining based on InGaP/GaAs HBT is developed and measured for the application of the latest high power amplifier stage of the X-band. A novel InGaP/GaAs HBT power transistor with an on-chip RC stabilization network is used as the power combing cell to improve the stability of the circuit. A compact mi- crostripe line parallel matching network is used to divide and combine the power. By biasing the amplifier at class AB： Vc= 7V, Ic = 230mA,a maximum CW stabile output power of 28.9dBm and a power combine efficiency of 80% are achieved at 8. 1GHz.展开更多
To meet the escalating electricity demand and rising fuel costs,along with notable losses in power transmission,exploring alternative solutions is imperative.Gas turbines demonstrate high efficiency under ideal Intern...To meet the escalating electricity demand and rising fuel costs,along with notable losses in power transmission,exploring alternative solutions is imperative.Gas turbines demonstrate high efficiency under ideal International Organization for Standardization(ISO)conditions but face challenges during summer when ambient temperatures reach 40℃.To enhance performance,the proposal suggests cooling inlet air by 15℃using a vapor absorption chiller(VAC),utilizing residual exhaust gases from a combined cycle power plant(CCPP)to maximize power output.Additionally,diverting a portion of exhaust gases to drive an organic Rankine cycle(ORC)for supplementary power generation offers added efficiency.This integrated approach not only boosts power output but alsominimizes environmental impact by repurposing exhaust gases for additional operations.This study presents a detailed energy and economic analysis of a modified combine cycle power plant,in Kotri,Pakistan.R600A is used as organic fuel for the ORC while LiBr-H2O solution is used for the VAC.Two performance parameters,efficiency and energy utilization factor,Four energetic parameters,Work output of ORC,modified CCPP,original CCPP and cooling rate,and one economics parameter,payback period were examined under varying ambient conditions and mass fraction of exhaust gases from outlet of a gas turbine(ψ).A parametric investigation was conducted within the temperature range of 18℃to 50℃,relative humidity between 70%and 90%,and theψranging from 0 to 0.3.The findings reveal that under elevated ambient conditions(40℃,90%humidity)withψat 0,the Energy Utilization Factor(EUF)exceeds 60%.However,the ORC exhibits a low work output of 100KWalongside a high cooling load of 29,000 kW.Conversely,the modified system demonstrates an augmented work output of approximately 81,850 KWcompared to the original system’s 78,500KW.Furthermore,the integration of this systemproves advantageous across all metrics.Additionally,the payback period of the system is contingent on ambient conditions,with lower conditions correlating to shorter payback periods and vice versa.展开更多
Combined Heat and Power Economic Dispatch(CHPED)is an important problem in the energy field,and it is beneficial for improving the utilization efficiency of power and heat energies.This paper proposes a Modified Genet...Combined Heat and Power Economic Dispatch(CHPED)is an important problem in the energy field,and it is beneficial for improving the utilization efficiency of power and heat energies.This paper proposes a Modified Genetic Algorithm(MGA)to determine the power and heat outputs of three kinds of units for CHPED.First,MGA replaces the simulated binary crossover by a new one based on the uniform and guassian distributions,and its convergence can be enhanced.Second,MGA modi-fies the mutation operator by introducing a disturbance coefficient based on guassian distribution,which can decrease the risk of being trapped into local optima.Eight instances with or without prohibited operating zones are used to investigate the efficiencies of MGA and other four genetic algorithms for CHPED.In comparison with the other algorithms,MGA has reduced generation costs by at least 562.73$,1068.7$,522.68$and 1016.24$,respectively,for instances 3,4,7 and 8,and it has reduced generation costs by at most 848.22$,3642.85$,897.63$and 3812.65$,respectively,for instances 3,4,7 and 8.Therefore,MGA has desirable convergence and stability for CHPED in comparison with the other four genetic algorithms.展开更多
8GHz 20W internally matched A1GaN/GaN HEMTs have been developed. The input and output matching net- works are realised with microstrip lines on a 0. 381mm thick alumina substrate. To improve the stability factor K of ...8GHz 20W internally matched A1GaN/GaN HEMTs have been developed. The input and output matching net- works are realised with microstrip lines on a 0. 381mm thick alumina substrate. To improve the stability factor K of the device, a lossy RC network is used at the input of the device. The developed internally matched power amplifier module exhibits 43dBm （20W） power output with a 7.3dB linear gain,38.1% PAIE,and combined power efficiency of 70.6% at 8GHz.展开更多
In view of the existing design challenges for Terahertz(THz)power amplifiers(PAs),the common design methods and the efforts of the State Key Laboratory of Millimeter Wave,Southeast University,China in the development ...In view of the existing design challenges for Terahertz(THz)power amplifiers(PAs),the common design methods and the efforts of the State Key Laboratory of Millimeter Wave,Southeast University,China in the development of silicon-based THz PAs,mainly including silicon-based PAs with operating frequencies covering 100–300 GHz,are summarized in this paper.Particularly,we design an LC-balun-based two-stage differential cascode PA with a center frequency of 150 GHz and an output power of 14 dBm.Based on a Marchand balun,we report a 220 GHz three-stage differential cascode PA with a saturated output power of 9.5 dBm.To further increase the output power of THz PA,based on a four-way differential power combining technique,we report a 211–263 GHz dual-LC-tank-based broadband PA with a recorded 14.7 dBm Psat and 16.4 dB peak gain.All the above circuits are designed in a standard 130 nm silicon germanium(SiGe)BiCMOS process.展开更多
This paper briefs the configuration and performance of large size gas turbines and their composed combined cycle power plants designed and produced by four large renown gas turbine manufacturing firms in the world, pr...This paper briefs the configuration and performance of large size gas turbines and their composed combined cycle power plants designed and produced by four large renown gas turbine manufacturing firms in the world, providing reference for the relevant sectors and enterprises in importing advanced gas turbines and technologies.展开更多
To improve the overall thermal efficiency of the organic Rankine cycle（ ORC）, a simulation study was carried out for a combined heat and power（ CHP） system, using the Redlich-Kuang-Soave（ RKS） equation of state....To improve the overall thermal efficiency of the organic Rankine cycle（ ORC）, a simulation study was carried out for a combined heat and power（ CHP） system, using the Redlich-Kuang-Soave（ RKS） equation of state. In the system,R245 fa was selected as the working fluid. A scroll expander was modeled with empirical isentropic expansion efficiency.Plate heat exchangers were selected as the evaporator and the condenser, and detailed heat transfer models were programmed for both one-phase and two-phase regions. Simulations were carried out at seven different heat source temperatures（ 80,90, 100, 110, 120, 130, 140 ℃） in combination with eight different heat sink temperatures（ 20, 25, 30, 35, 40, 45, 50,55 ℃）. Results showthat in the ORC without an internal heat exchanger（ IHE）, the optimum cycle efficiencies are in the range of 7. 0% to 7. 3% when the temperature differences between the heat source and heat sink are in the range of 70 to90 ℃. Simulations on CHP reveal that domestic hot water can be produced when the heat sink inlet temperature is higher than40 ℃, and the corresponding exergy efficiency and overall thermal efficiency are 29% to 56% and 87% to 90% higher than those in the non-CHP ORC, respectively. It is found that the IHE has little effect on the improvement of work output and efficiencies for the CHP ORC.展开更多
Unlike the traditional traction power supply system which enables the electrified railway traction sub- station to be connected to power grid in a way of phase rotation, a new generation traction power supply system w...Unlike the traditional traction power supply system which enables the electrified railway traction sub- station to be connected to power grid in a way of phase rotation, a new generation traction power supply system without phase splits is proposed in this paper. Three key techniques used in this system have been discussed. First, a combined co-phase traction power supply system is applied at traction substations for compensating negative sequence current and eliminating phase splits at exits of substations; design method and procedure for this system are presented. Second, a new bilateral traction power supply technology is proposed to eliminate the phase split at section post and reduce the influence of equalizing current on the power grid. Meanwhile, power factor should be adjusted to ensure a proper voltage level of the traction network. Third, a seg- mental power supply technology of traction network is used to divide the power supply arms into several segments, and the synchronous measurement and control technology is applied to diagnose faults and their locations quickly and accurately. Thus, the fault impact can be limited to a min- imum degree. In addition, the economy and reliability of the new generation traction power supply system are analyzed.展开更多
This paper built a combined heat and power（CHP） dispatch model for wind-CHP system with solid heat storage device（SHS） aiming at minimizing system coal consumption, and set system demand-supply balance and units＇...This paper built a combined heat and power（CHP） dispatch model for wind-CHP system with solid heat storage device（SHS） aiming at minimizing system coal consumption, and set system demand-supply balance and units＇ operation conditions as the operation constraints. Furthermore, robust stochastic optimization theory was used to describe wind power output uncertainty. The simulation result showed that SHS increased CHP peak-valley shifting capability and reduced abandoned wind rate from 12% to 6%, and reduced 5% coal consumption, compared with the original system operation by flexible charging electric power and heating. The payback period of employing SHS in wind-CHP system is far shorter than SHS expected service life.展开更多
Combined heat and power （CHP） refers to a process/system designed to utilize the waste or residual heat from a power generation process. Thus, a CHP plant can produce both electricity and heat. The nature of such a ...Combined heat and power （CHP） refers to a process/system designed to utilize the waste or residual heat from a power generation process. Thus, a CHP plant can produce both electricity and heat. The nature of such a combination makes the process more complex than any single power generation process or boiler heating system. The paper focuses on modelling study and analysis of energy efficiency of the University of Warwick micro-CHP power plant. In this CHP modelling study, a gas turbine module is built to provide driving power and methane is used as fuel gas. Heat recovery system and auxiliary boiler modules are developed for thermal power generation. All the sub-systems are validated by comparing the simulation results with the operating data collected from the CHP plant. The dynamic performance of the key CHP process outputs is studied with respect to the variation of the input syngas stream, including electricity generation, thermal power output and water output temperature. Simplified controllers are also applied to the gas engineheat recovery subsystem and auxiliary boiler. Simulation results with/without feedback control are both analyzed. The study has highlighted the key factors which influence the plant performance and suggested the strategy for potential energy efficiency improvement.展开更多
This paper presents the solution to the combined heat and power economic dispatch problem using a direct solution algorithm for constrained optimization problems. With the potential of Combined Heat and Power (CHP) pr...This paper presents the solution to the combined heat and power economic dispatch problem using a direct solution algorithm for constrained optimization problems. With the potential of Combined Heat and Power (CHP) production to increase the efficiency of power and heat generation simultaneously having been researched and established, the increasing penetration of CHP systems, and determination of economic dispatch of power and heat assumes higher relevance. The Combined Heat and Power Economic Dispatch (CHPED) problem is a demanding optimization problem as both constraints and objective functions can be non-linear and non-convex. This paper presents an explicit formula developed for computing the system-wide incremental costs corresponding with optimal dispatch. The circumvention of the use of iterative search schemes for this crucial step is the innovation inherent in the proposed dispatch procedure. The feasible operating region of the CHP unit three is taken into account in the proposed CHPED problem model, whereas the optimal dispatch of power/heat outputs of CHP unit is determined using the direct Lagrange multiplier solution algorithm. The proposed algorithm is applied to a test system with four units and results are provided.展开更多
A method of designing an E-plane power combiner composed of two quarter-arc bent rectangular waveguides is proposed for sub-THz and THz waves. The quarter-arc bent-waveguide power combiner has a simple geometry which ...A method of designing an E-plane power combiner composed of two quarter-arc bent rectangular waveguides is proposed for sub-THz and THz waves. The quarter-arc bent-waveguide power combiner has a simple geometry which is easy to design and fabricate. By HFSS codes, the physical mechanism and performance of the power combiner are analyzed, and the relationship between the output characteristics and the structure/operating parameters is given. Simulation results show that our power combiner is suitable for the combining of two equalpower and reversed-phase signals, the bandwidth of the combiner is wide and can be adjusted by the radius of the quarter-arc, and the isolation performance of the combiner can be improved by adding thin film resistive septa at the junction of two quarter-arc bent waveguides. Meanwhile, an approximate method based on the analytic geometrical analysis is given to design this power combiner for different frequency bands.展开更多
The electromagnetic time-reversal(TR)technique has the characteristics of spatiotemporal focusing in a time-reversal cavity(TRC),which can be used for pulse compression,thus forming an electromagnetic pulse with high ...The electromagnetic time-reversal(TR)technique has the characteristics of spatiotemporal focusing in a time-reversal cavity(TRC),which can be used for pulse compression,thus forming an electromagnetic pulse with high peak power.A time-reversed pulse-compression method in a single channel has high pulse compression gain.However,single channel pulse compression can only generate limited gain.This paper proposes a novel TR power-combination method in a multichannel TRC to obtain higher peak power based on TR pulse-compression theory.First,the TR power-combination model is given,and the crosstalk properties of the associated channel and the influence of the reversal performance are studied.Then,the power-combination performances for the TR pulse compression,such as combined signal to noise ratio(SNR)and combined compression gain,are analyzed by numerical simulation and experimental methods.The results show that the proposed method has obvious advantages over pulse-compression methods using a single channel cavity,and is more convenient for power combination.展开更多
This article presents the design and performance of a terahertz on-chip coupled-grounded coplanar waveguide(GCPW)power combiner using a 50μm-thick InP process.The proposed topology uses two coupled-GCPW lines at the ...This article presents the design and performance of a terahertz on-chip coupled-grounded coplanar waveguide(GCPW)power combiner using a 50μm-thick InP process.The proposed topology uses two coupled-GCPW lines at the end of the input port to substitute two quarter-wavelength GCPW lines,which is different from the conventional Wilkinson power combiner and can availably minimize the coverage area.According to the results obtained,for the frequency range of 210-250 GHz,the insertion losses for each two-way combiner and four-way combiner were lower than 1.05 dB and1.35 dB,respectively,and the in-band return losses were better than 11 dB.Moreover,the proposed on-chip GCPW-based combiners achieved a compromise in low-loss,broadband,and small-size,which can find wide applications in terahertz bands,such as power amplifiers and signal distribution networks.展开更多
In order to improve efficiency of a combined power system in which waste heat from exhaust gas could be efficiently recovered and cold energ^^ of liquefied natural gas （LNG） could be fully utilized as well. A system...In order to improve efficiency of a combined power system in which waste heat from exhaust gas could be efficiently recovered and cold energ^^ of liquefied natural gas （LNG） could be fully utilized as well. A system simulation and ther^nodynamic analysis were carried out, the Kalina cycle was reorganized by changing the concentration of “basic composition”, so that a better thermal matching in the heat exchanger could be obtained and the irreversibility of the system was decreased. It was found that the Kalina cycle generally used in the bottom of combined power cycle could also be used to recover the cold energy of LNG. The results show that the exergy efficiency of 42.97% is obtained. Compared with the previous system attained the exergy efficiency of 39.76%, the improved system has a better performance.展开更多
The South China Sea is rich in wind and wave energy resources,and the wind-wave combined power generation device is currently in the concept research and development stage.In recent years,extreme sea conditions such a...The South China Sea is rich in wind and wave energy resources,and the wind-wave combined power generation device is currently in the concept research and development stage.In recent years,extreme sea conditions such as super typhoons have frequently occurred,which poses a serious challenge to the safety of offshore floating platforms.In view of the lack of safety analysis of wind-wave combined power generation devices in extreme sea conditions at present,this paper takes the OC4-WEC combined with semi-submersible wind turbine(Semi-OC4)and the oscillating buoy wave energy converter as the research object,and establishes a mesoscale WRF-SWANFVCOM(W-S-F)real-time coupling platform based on the model coupling Toolkit(MCT)to analyze the spatial and temporal evolution of wind-wave-current in offshore wind farms during the whole process of super typhoon“Rammasun”transit.Combined with the medium/small scale nested method,the flow field characteristics of OC4-WEC platform are analyzed.The results show that the simulation accuracy of the established W-S-F platform for typhoon track is 42.51%higher than that of the single WRF model.Under the action of typhoon-wave-current,the heave motion amplitude of OC4-WEC platform is reduced by 38.1%,the surge motion amplitude is reduced by 26.7%,and the pitch motion amplitude is reduced by 23.4%.展开更多
Aiming at the problems of large-scale wind and solar grid connection,how to ensure the economy of system operation and how to realize fair scheduling between new energy power stations,a two-stage optimal dispatching m...Aiming at the problems of large-scale wind and solar grid connection,how to ensure the economy of system operation and how to realize fair scheduling between new energy power stations,a two-stage optimal dispatching model of wind power-photovoltaic-solar thermal combined system considering economic optimality and fairness is proposed.Firstly,the first stage dispatching model takes the overall economy optimization of the system as the goal and the principle of maximizing the consumption of wind and solar output,obtains the optimal output value under the economic conditions of each new energy station,and then obtains the maximum consumption space of the new energy station.Secondly,based on the optimization results of the first stage,the second stage dispatching model uses the dispatching method of fuzzy comprehensive ranking priority to prioritize the new energy stations,and then makes a fair allocation to the dispatching of the wind and solar stations.Finally,the analysis of a specific example shows that themodel can take into account the fairness of active power distribution of new energy stations on the basis of ensuring the economy of system operation,make full use of the consumption space,and realize the medium and long-term fairness distribution of dispatching plan.展开更多
As a potentially viable renewable energy, Enhanced Geothermal Systems(EGSs) extract heat from hot dry rock(HDR) reservoirs to produce electricity and heat, which promotes the progress towards carbon peaking and carbon...As a potentially viable renewable energy, Enhanced Geothermal Systems(EGSs) extract heat from hot dry rock(HDR) reservoirs to produce electricity and heat, which promotes the progress towards carbon peaking and carbon neutralization. The main challenge for EGSs is to reduce the investment cost. In the present study, thermo-economic investigations of EGS projects are conducted. The effects of geofluid mass flow rate, wellhead temperature and loss rate on the thermo-economic performance of the EGS organic Rankine cycle(ORC) are studied. A performance comparison between EGS-ORC and the EGS combined heating and power system(CHP) is presented. Considering the CO_(2)emission reduction benefits, the influence of carbon emission trading price on the levelized cost of energy(LCOE) is also presented. It is indicated that the geofluid mass flow rate is a critical parameter in dictating the success of a project. Under the assumed typical working conditions, the LCOE of EGS-ORC and EGS-CHP systems are 24.72 and 16.1 cents/k Wh, respectively. Compared with the EGS-ORC system, the LCOE of the EGS-CHP system is reduced by 35%. EGS-CHP systems have the potential to be economically viable in the future. With carbon emission trading prices of 12.76 USD/ton, the LCOE can be reduced by approximately 8.5%.展开更多
基金National Key Research and Development Program of China(2022YFF0707602)National Natural Science Foundation of China(62471097,62471115,62471101)National Natural Science Foundation of Sichuan(2025ZNSFSC0537)。
文摘[Background]Traveling-wave tubes(TWTs)are widely applied in radar,imaging,and military systems owing to their excellent amplification characteristics.Miniaturization and integration are critical to the future of TWTs,with multi-channel slow-wave structures(SWSs)forming the foundation for their realization in high-power vacuum electronic devices.[Purpose]To provide design insights for multi-channel TWTs and simultaneously enhance their output power,a W-band folded-waveguide TWT with dual electron beams and H-plane power combining was proposed.[Methods]Three-dimensional electromagnetic simulations in CST were conducted to verify the highfrequency characteristics,electric field distribution,and amplification performance of the proposed SWS,thereby confirming the validity of the design.[Results]Results indicate that the designed TWT achieves a transmission bandwidth of 10 GHz.With an electron beam voltage of 17.9 kV and a current of 0.35 A,the output power reaches 450 W at 94 GHz,corresponding to an efficiency of 7.18%and a gain of 23.5 dB.Moreover,under fixed beam voltage and current,the TWT delivers over 200 W output power across 91–99 GHz,with a 3 dB bandwidth of 91–98.5 GHz.The particle voltage distribution after modulation further validates the mode analysis.[Conclusions]These results demonstrate the feasibility of compact dual-beam power-combining structures and provide useful guidance for the design of future multi-channel TWTs.
文摘A power amplifier MIC with power combining based on AlGaN/GaN HEMTs was fabricated and measured. The amplifier consists of four 10 × 120μm transistors. A Wilkinson splitters and combining were used to divide and combine the power. By biasing the amplifier at VDS = 40V, IDS = 0.9A, a maximum CW output power of 41.4dBm with a maximum power added efficiency （PAE） of 32.54% and a power combine efficiency of 69% was achieved at 5.4GHz.
文摘A MIC power amplifier with power combining based on InGaP/GaAs HBT is developed and measured for the application of the latest high power amplifier stage of the X-band. A novel InGaP/GaAs HBT power transistor with an on-chip RC stabilization network is used as the power combing cell to improve the stability of the circuit. A compact mi- crostripe line parallel matching network is used to divide and combine the power. By biasing the amplifier at class AB： Vc= 7V, Ic = 230mA,a maximum CW stabile output power of 28.9dBm and a power combine efficiency of 80% are achieved at 8. 1GHz.
文摘To meet the escalating electricity demand and rising fuel costs,along with notable losses in power transmission,exploring alternative solutions is imperative.Gas turbines demonstrate high efficiency under ideal International Organization for Standardization(ISO)conditions but face challenges during summer when ambient temperatures reach 40℃.To enhance performance,the proposal suggests cooling inlet air by 15℃using a vapor absorption chiller(VAC),utilizing residual exhaust gases from a combined cycle power plant(CCPP)to maximize power output.Additionally,diverting a portion of exhaust gases to drive an organic Rankine cycle(ORC)for supplementary power generation offers added efficiency.This integrated approach not only boosts power output but alsominimizes environmental impact by repurposing exhaust gases for additional operations.This study presents a detailed energy and economic analysis of a modified combine cycle power plant,in Kotri,Pakistan.R600A is used as organic fuel for the ORC while LiBr-H2O solution is used for the VAC.Two performance parameters,efficiency and energy utilization factor,Four energetic parameters,Work output of ORC,modified CCPP,original CCPP and cooling rate,and one economics parameter,payback period were examined under varying ambient conditions and mass fraction of exhaust gases from outlet of a gas turbine(ψ).A parametric investigation was conducted within the temperature range of 18℃to 50℃,relative humidity between 70%and 90%,and theψranging from 0 to 0.3.The findings reveal that under elevated ambient conditions(40℃,90%humidity)withψat 0,the Energy Utilization Factor(EUF)exceeds 60%.However,the ORC exhibits a low work output of 100KWalongside a high cooling load of 29,000 kW.Conversely,the modified system demonstrates an augmented work output of approximately 81,850 KWcompared to the original system’s 78,500KW.Furthermore,the integration of this systemproves advantageous across all metrics.Additionally,the payback period of the system is contingent on ambient conditions,with lower conditions correlating to shorter payback periods and vice versa.
基金supported by the National Natural Science Foundation of China(NSFC)under Grant 61873272,62073327in part by the Natural Science Foundation of Jiangsu Province under Grant BK20200086,BK20200631.
文摘Combined Heat and Power Economic Dispatch(CHPED)is an important problem in the energy field,and it is beneficial for improving the utilization efficiency of power and heat energies.This paper proposes a Modified Genetic Algorithm(MGA)to determine the power and heat outputs of three kinds of units for CHPED.First,MGA replaces the simulated binary crossover by a new one based on the uniform and guassian distributions,and its convergence can be enhanced.Second,MGA modi-fies the mutation operator by introducing a disturbance coefficient based on guassian distribution,which can decrease the risk of being trapped into local optima.Eight instances with or without prohibited operating zones are used to investigate the efficiencies of MGA and other four genetic algorithms for CHPED.In comparison with the other algorithms,MGA has reduced generation costs by at least 562.73$,1068.7$,522.68$and 1016.24$,respectively,for instances 3,4,7 and 8,and it has reduced generation costs by at most 848.22$,3642.85$,897.63$and 3812.65$,respectively,for instances 3,4,7 and 8.Therefore,MGA has desirable convergence and stability for CHPED in comparison with the other four genetic algorithms.
文摘8GHz 20W internally matched A1GaN/GaN HEMTs have been developed. The input and output matching net- works are realised with microstrip lines on a 0. 381mm thick alumina substrate. To improve the stability factor K of the device, a lossy RC network is used at the input of the device. The developed internally matched power amplifier module exhibits 43dBm （20W） power output with a 7.3dB linear gain,38.1% PAIE,and combined power efficiency of 70.6% at 8GHz.
基金supported in part by the National Natural Science Foundation of China under Grant Nos.62101117 and 62188102in part by ZTE Industry-University-Institute Cooperation Fundsin part by the Project funded by China Postdoctoral Science Foundation under Grant Nos.2021M700763 and 2022T150113.
文摘In view of the existing design challenges for Terahertz(THz)power amplifiers(PAs),the common design methods and the efforts of the State Key Laboratory of Millimeter Wave,Southeast University,China in the development of silicon-based THz PAs,mainly including silicon-based PAs with operating frequencies covering 100–300 GHz,are summarized in this paper.Particularly,we design an LC-balun-based two-stage differential cascode PA with a center frequency of 150 GHz and an output power of 14 dBm.Based on a Marchand balun,we report a 220 GHz three-stage differential cascode PA with a saturated output power of 9.5 dBm.To further increase the output power of THz PA,based on a four-way differential power combining technique,we report a 211–263 GHz dual-LC-tank-based broadband PA with a recorded 14.7 dBm Psat and 16.4 dB peak gain.All the above circuits are designed in a standard 130 nm silicon germanium(SiGe)BiCMOS process.
文摘This paper briefs the configuration and performance of large size gas turbines and their composed combined cycle power plants designed and produced by four large renown gas turbine manufacturing firms in the world, providing reference for the relevant sectors and enterprises in importing advanced gas turbines and technologies.
基金Special Fund for IndustryUniversity and Research Cooperation(No.2011DFR61130)
文摘To improve the overall thermal efficiency of the organic Rankine cycle（ ORC）, a simulation study was carried out for a combined heat and power（ CHP） system, using the Redlich-Kuang-Soave（ RKS） equation of state. In the system,R245 fa was selected as the working fluid. A scroll expander was modeled with empirical isentropic expansion efficiency.Plate heat exchangers were selected as the evaporator and the condenser, and detailed heat transfer models were programmed for both one-phase and two-phase regions. Simulations were carried out at seven different heat source temperatures（ 80,90, 100, 110, 120, 130, 140 ℃） in combination with eight different heat sink temperatures（ 20, 25, 30, 35, 40, 45, 50,55 ℃）. Results showthat in the ORC without an internal heat exchanger（ IHE）, the optimum cycle efficiencies are in the range of 7. 0% to 7. 3% when the temperature differences between the heat source and heat sink are in the range of 70 to90 ℃. Simulations on CHP reveal that domestic hot water can be produced when the heat sink inlet temperature is higher than40 ℃, and the corresponding exergy efficiency and overall thermal efficiency are 29% to 56% and 87% to 90% higher than those in the non-CHP ORC, respectively. It is found that the IHE has little effect on the improvement of work output and efficiencies for the CHP ORC.
基金supported by the National Natural Science Funds of China (Nos. 51307143 and 51307142)Technology Research and Development Program of China Railway Corporation (No. 2014J009-B)
文摘Unlike the traditional traction power supply system which enables the electrified railway traction sub- station to be connected to power grid in a way of phase rotation, a new generation traction power supply system without phase splits is proposed in this paper. Three key techniques used in this system have been discussed. First, a combined co-phase traction power supply system is applied at traction substations for compensating negative sequence current and eliminating phase splits at exits of substations; design method and procedure for this system are presented. Second, a new bilateral traction power supply technology is proposed to eliminate the phase split at section post and reduce the influence of equalizing current on the power grid. Meanwhile, power factor should be adjusted to ensure a proper voltage level of the traction network. Third, a seg- mental power supply technology of traction network is used to divide the power supply arms into several segments, and the synchronous measurement and control technology is applied to diagnose faults and their locations quickly and accurately. Thus, the fault impact can be limited to a min- imum degree. In addition, the economy and reliability of the new generation traction power supply system are analyzed.
基金Supported by the Fundamental Research Funds for the National Science Foundation of China(71573084)
文摘This paper built a combined heat and power（CHP） dispatch model for wind-CHP system with solid heat storage device（SHS） aiming at minimizing system coal consumption, and set system demand-supply balance and units＇ operation conditions as the operation constraints. Furthermore, robust stochastic optimization theory was used to describe wind power output uncertainty. The simulation result showed that SHS increased CHP peak-valley shifting capability and reduced abandoned wind rate from 12% to 6%, and reduced 5% coal consumption, compared with the original system operation by flexible charging electric power and heating. The payback period of employing SHS in wind-CHP system is far shorter than SHS expected service life.
基金supported by Engineering and Physical Sciences Research Council(No.EP/I010955/1)Chinese Scholarship Council(CSC)
文摘Combined heat and power （CHP） refers to a process/system designed to utilize the waste or residual heat from a power generation process. Thus, a CHP plant can produce both electricity and heat. The nature of such a combination makes the process more complex than any single power generation process or boiler heating system. The paper focuses on modelling study and analysis of energy efficiency of the University of Warwick micro-CHP power plant. In this CHP modelling study, a gas turbine module is built to provide driving power and methane is used as fuel gas. Heat recovery system and auxiliary boiler modules are developed for thermal power generation. All the sub-systems are validated by comparing the simulation results with the operating data collected from the CHP plant. The dynamic performance of the key CHP process outputs is studied with respect to the variation of the input syngas stream, including electricity generation, thermal power output and water output temperature. Simplified controllers are also applied to the gas engineheat recovery subsystem and auxiliary boiler. Simulation results with/without feedback control are both analyzed. The study has highlighted the key factors which influence the plant performance and suggested the strategy for potential energy efficiency improvement.
文摘This paper presents the solution to the combined heat and power economic dispatch problem using a direct solution algorithm for constrained optimization problems. With the potential of Combined Heat and Power (CHP) production to increase the efficiency of power and heat generation simultaneously having been researched and established, the increasing penetration of CHP systems, and determination of economic dispatch of power and heat assumes higher relevance. The Combined Heat and Power Economic Dispatch (CHPED) problem is a demanding optimization problem as both constraints and objective functions can be non-linear and non-convex. This paper presents an explicit formula developed for computing the system-wide incremental costs corresponding with optimal dispatch. The circumvention of the use of iterative search schemes for this crucial step is the innovation inherent in the proposed dispatch procedure. The feasible operating region of the CHP unit three is taken into account in the proposed CHPED problem model, whereas the optimal dispatch of power/heat outputs of CHP unit is determined using the direct Lagrange multiplier solution algorithm. The proposed algorithm is applied to a test system with four units and results are provided.
基金Supported by the National Natural Science Foundation of China under Grant No 11075032the Fundamental Research Funds for the Central Universities under Grant No ZYGX2014J033
文摘A method of designing an E-plane power combiner composed of two quarter-arc bent rectangular waveguides is proposed for sub-THz and THz waves. The quarter-arc bent-waveguide power combiner has a simple geometry which is easy to design and fabricate. By HFSS codes, the physical mechanism and performance of the power combiner are analyzed, and the relationship between the output characteristics and the structure/operating parameters is given. Simulation results show that our power combiner is suitable for the combining of two equalpower and reversed-phase signals, the bandwidth of the combiner is wide and can be adjusted by the radius of the quarter-arc, and the isolation performance of the combiner can be improved by adding thin film resistive septa at the junction of two quarter-arc bent waveguides. Meanwhile, an approximate method based on the analytic geometrical analysis is given to design this power combiner for different frequency bands.
基金Project supported by the National Key R&D Program of China(Grant No.2021YFC2203503)。
文摘The electromagnetic time-reversal(TR)technique has the characteristics of spatiotemporal focusing in a time-reversal cavity(TRC),which can be used for pulse compression,thus forming an electromagnetic pulse with high peak power.A time-reversed pulse-compression method in a single channel has high pulse compression gain.However,single channel pulse compression can only generate limited gain.This paper proposes a novel TR power-combination method in a multichannel TRC to obtain higher peak power based on TR pulse-compression theory.First,the TR power-combination model is given,and the crosstalk properties of the associated channel and the influence of the reversal performance are studied.Then,the power-combination performances for the TR pulse compression,such as combined signal to noise ratio(SNR)and combined compression gain,are analyzed by numerical simulation and experimental methods.The results show that the proposed method has obvious advantages over pulse-compression methods using a single channel cavity,and is more convenient for power combination.
基金Project supported in part by the National Natural Science Foundation of China(Grant No.61871072)。
文摘This article presents the design and performance of a terahertz on-chip coupled-grounded coplanar waveguide(GCPW)power combiner using a 50μm-thick InP process.The proposed topology uses two coupled-GCPW lines at the end of the input port to substitute two quarter-wavelength GCPW lines,which is different from the conventional Wilkinson power combiner and can availably minimize the coverage area.According to the results obtained,for the frequency range of 210-250 GHz,the insertion losses for each two-way combiner and four-way combiner were lower than 1.05 dB and1.35 dB,respectively,and the in-band return losses were better than 11 dB.Moreover,the proposed on-chip GCPW-based combiners achieved a compromise in low-loss,broadband,and small-size,which can find wide applications in terahertz bands,such as power amplifiers and signal distribution networks.
基金Sponsored by the Liaoning Provincial Science and Technology Program Project(Grant No.2012219024)
文摘In order to improve efficiency of a combined power system in which waste heat from exhaust gas could be efficiently recovered and cold energ^^ of liquefied natural gas （LNG） could be fully utilized as well. A system simulation and ther^nodynamic analysis were carried out, the Kalina cycle was reorganized by changing the concentration of “basic composition”, so that a better thermal matching in the heat exchanger could be obtained and the irreversibility of the system was decreased. It was found that the Kalina cycle generally used in the bottom of combined power cycle could also be used to recover the cold energy of LNG. The results show that the exergy efficiency of 42.97% is obtained. Compared with the previous system attained the exergy efficiency of 39.76%, the improved system has a better performance.
基金jointly funded by the National Key Research and Development Projects(No.2017YFE0132000)the National Natural Science Foundation of China(Nos.5211101879,52078251,52108456)the Natural Science Foundation of Jiangsu Province(Nos.BK20211518,BK20210309)
文摘The South China Sea is rich in wind and wave energy resources,and the wind-wave combined power generation device is currently in the concept research and development stage.In recent years,extreme sea conditions such as super typhoons have frequently occurred,which poses a serious challenge to the safety of offshore floating platforms.In view of the lack of safety analysis of wind-wave combined power generation devices in extreme sea conditions at present,this paper takes the OC4-WEC combined with semi-submersible wind turbine(Semi-OC4)and the oscillating buoy wave energy converter as the research object,and establishes a mesoscale WRF-SWANFVCOM(W-S-F)real-time coupling platform based on the model coupling Toolkit(MCT)to analyze the spatial and temporal evolution of wind-wave-current in offshore wind farms during the whole process of super typhoon“Rammasun”transit.Combined with the medium/small scale nested method,the flow field characteristics of OC4-WEC platform are analyzed.The results show that the simulation accuracy of the established W-S-F platform for typhoon track is 42.51%higher than that of the single WRF model.Under the action of typhoon-wave-current,the heave motion amplitude of OC4-WEC platform is reduced by 38.1%,the surge motion amplitude is reduced by 26.7%,and the pitch motion amplitude is reduced by 23.4%.
基金a phased achievement of Gansu Province’s Major Science and Technology Project(19ZD2GA003)“Key Technologies and Demonstrative Applications of Market Consumption and Dispatching Control of Photothermal-Photovoltaic-Wind PowerNew Energy Base(Multi Energy System Optimization)”.
文摘Aiming at the problems of large-scale wind and solar grid connection,how to ensure the economy of system operation and how to realize fair scheduling between new energy power stations,a two-stage optimal dispatching model of wind power-photovoltaic-solar thermal combined system considering economic optimality and fairness is proposed.Firstly,the first stage dispatching model takes the overall economy optimization of the system as the goal and the principle of maximizing the consumption of wind and solar output,obtains the optimal output value under the economic conditions of each new energy station,and then obtains the maximum consumption space of the new energy station.Secondly,based on the optimization results of the first stage,the second stage dispatching model uses the dispatching method of fuzzy comprehensive ranking priority to prioritize the new energy stations,and then makes a fair allocation to the dispatching of the wind and solar stations.Finally,the analysis of a specific example shows that themodel can take into account the fairness of active power distribution of new energy stations on the basis of ensuring the economy of system operation,make full use of the consumption space,and realize the medium and long-term fairness distribution of dispatching plan.
基金financial support provided by the National Key Research and Development Program of China(No.2018YFB1501805)China Geological Survey Project(Grant No.DD2019135,and No.DD20211336)。
文摘As a potentially viable renewable energy, Enhanced Geothermal Systems(EGSs) extract heat from hot dry rock(HDR) reservoirs to produce electricity and heat, which promotes the progress towards carbon peaking and carbon neutralization. The main challenge for EGSs is to reduce the investment cost. In the present study, thermo-economic investigations of EGS projects are conducted. The effects of geofluid mass flow rate, wellhead temperature and loss rate on the thermo-economic performance of the EGS organic Rankine cycle(ORC) are studied. A performance comparison between EGS-ORC and the EGS combined heating and power system(CHP) is presented. Considering the CO_(2)emission reduction benefits, the influence of carbon emission trading price on the levelized cost of energy(LCOE) is also presented. It is indicated that the geofluid mass flow rate is a critical parameter in dictating the success of a project. Under the assumed typical working conditions, the LCOE of EGS-ORC and EGS-CHP systems are 24.72 and 16.1 cents/k Wh, respectively. Compared with the EGS-ORC system, the LCOE of the EGS-CHP system is reduced by 35%. EGS-CHP systems have the potential to be economically viable in the future. With carbon emission trading prices of 12.76 USD/ton, the LCOE can be reduced by approximately 8.5%.
